Succinimides and hydroxybenzylamines are generally known for conventional ashless dispersants. Owing to their specific ability to disperse fine particles, the compounds have heretofore been widely used for lubricant additives for gasoline engine oil, diesel engine oil, and 2-cycle engine oil. In addition, since their synergistic effect with zinc dialkyldithiophosphates, metal detergents of the like is considered good, the compounds are one group of extremely important lubricant additives. However, it is often said that they are unstable at high temperatures and their detergency at high temperature is not satisfactory.
For example, JP-B 43631/1971 discloses reaction products obtained through reaction of a reaction intermediate of alkylphenol, formaldehyde and polyalkylene-polyamine with a polyalkenylsuccinic anhydride, and reaction products obtained through further reaction of that reaction product with a boron-containing compounds, saying that those reaction products are effective for oxidation-stable, ashless detergent dispersants and that they have improved oil-solubility. JP-A 8304/1976 discloses reaction products obtained through reaction of a reaction intermediate of polyalkenylsuccinic acid (anhydride) and polyalkylene-polyamine with an aromatic alcohol (e.g., alkylphenol, phenol, thiodiphenol) in the presence of aldehyde. However, these reaction products are still unsatisfactory in point of their stability at high temperatures.
JP-A 168492/1988 discloses reaction products like in JP-B 43631/1971, for which, however, used is glycolic acid as the reactant and not a boron-containing compound. As in the prior-art references, however, the reaction products are also unsatisfactory in point of their stability at high temperatures.
JP-A 345690/1992 discloses succinimide compounds prepared from a polyalkylene-polyamine mixture that comprises both a cyclic polyalkylene-polyamine and an acyclic polyalkylene-polyamine. They have no negative influence on fluoroelastomer seals, but are almost ineffective for detergency at high temperatures.
JP-A 168492/1988 discloses reaction products like in JP-B 43631/1971, for which, however, used is glycolic acid as the reactant and not a boron-containing compound. As in the prior-art references, however, the reaction products are also unsatisfactory in point of their stability at high temperatures.
Other various proposals have been made in, for example, JP-A 69758/1986, 276896/1990 and 353598/1992, but could not still solve the problems noted above.
Given that situation, most desired in the industrial field of the art are lubricant additives and lubricants having good high-temperature stability and good high-temperature detergency.
The invention is to solve the above-mentioned drawbacks of the prior-art techniques, and to provide novel compounds having good high-temperature stability and good high-temperature detergency and therefore useful for ashless detergent dispersants having the ability to disperse fine particles; additives for lubricant and fuel oil that comprise the novel compound as the essential ingredient; and lubricants and fuel oil compositions that contain the additive.